The Philadelphia Zoo announced the hatching of four critically endangered Galápagos tortoises for the first time in the zoo's 150-year history, according to The New York Times.
The hatchlings are the offspring of Mommy and Abrazzo, two Western Santa Cruz tortoises and the zoo's two oldest residents, each estimated to be around 100 years old. Mommy recently became a first-time mother at this age.
"We couldn't be more excited to share this news with our city, region and the world," said Jo-Elle Mogerman, President and CEO of the Philadelphia Zoo, according to the New York Post.
"They are about the size of a tennis ball and they are pretty feisty, actually," said Lauren Augustine, Philadelphia Zoo Director of Herpetology. The hatchlings weigh between 70 and 80 grams, about the weight of a chicken egg.
Currently, the young tortoises are being kept behind the scenes inside the Reptile and Amphibian House, where they are "eating and growing appropriately," according to CBS News. The hatchlings will make their public debut on April 23, 2023, which is the 93rd anniversary of Mommy's arrival at the zoo, and the zoo plans a naming contest for them.
"These hatchlings not only protect this species from extinction, but serve as important ambassadors to inspire guests to save wildlife and wild places," said Rachel Metz, Philadelphia Zoo Vice President of Animal Well-Being and Conservation, according to Good News Network. Augustine added, "This successful outcome comes from years of hard work studying animal behavior and providing top-level care. Until now, Mommy's genes were not represented in the AZA population, making these offspring extremely important in the protection of this species," as reported by Good News Network.
Galápagos tortoises can live as long as 200 years, according to the Philadelphia Zoo. At one point, each of the Galápagos Islands had its own unique subspecies of tortoise with similar longevity. Sadly, several of these subspecies are now extinct.
"Centuries ago, the Galápagos tortoise population numbered in the hundreds of thousands," The New York Times reported. The population declined over time as they were hunted for human consumption. Due to conservation and breeding programs, "the Galápagos tortoise population has rebounded to around 17,000 in the last half-century," The New York Times noted.
Prior to the hatchlings' arrival, there were only 44 Western Santa Cruz giant tortoises in all U.S. zoos combined, according to The New York Times. Mommy is considered one of the most genetically valuable Galápagos tortoises in the Association of Zoos and Aquariums' species survival plan, CBS News reported.
"This one reproducing tortoise, in my opinion, isn't going to do much for what's going on in the wild in direct terms," said Dr. Stephen Blake, an assistant professor of biology at St. Louis University, according to The New York Times. "But in indirect terms, if the zoo can promote the wonder of a 100-year-old reptile producing babies for the first time and use that as a vehicle to promote wonder among people and a conservation ethic, then so much the better," Blake added.
"Every additional tortoise counts," said Juan Manuel Vazquez, a biologist who has studied aging in long-living animals, including Galápagos tortoises, according to The New York Times.
Mommy laid 16 eggs in November 2022, and the reptile and amphibian team dug them up to incubate, expecting them to hatch between four and eight months later. The first three rounds of Mommy's eggs were not viable. The zoo staff set the eggs up to be artificially incubated at two different temperatures: one known to produce female offspring and a higher temperature known to produce males. So far, the four hatchlings born this year are all female.
The hatchlings are being kept separate from their parents to prevent any risk of them being crushed. "The baby tortoises will likely never share the same physical space as their parents," The New York Times reported. After five years, the zoo will determine what to do with the hatchlings in consultation with the Association of Zoos and Aquariums.
Abrazzo came to the Philadelphia Zoo on the recommendation of the Association of Zoos and Aquariums. He arrived in December 2020 from Riverbanks Zoo in South Carolina. Unlike Mommy, Abrazzo is not a first-time parent. In 2011, he was part of a successful pairing that led to the unexpected discovery of five hatchlings at his previous home, the Riverbanks Zoo and Garden in Columbia, South Carolina.
"These hatchlings could help raise awareness about giant tortoises generally," The New York Times reported. Because the population is small and reproduction in captivity is so uncommon, the hatchlings will give researchers a rare chance to study the tortoises from a young age in captivity.
"They're at extreme risk from natural disasters, disease potentially, climate change and invasive species," said Rachel Metz, according to The New York Times. "The hatchlings are doing fantastic," Augustine said.
The article was written with the assistance of a news analysis system.